Along the same lines as the concept of a limited set of basic tools is the often muttered MMO adage that there are less than a dozen quest objective types. I actually think it's a lot less than 12. In fact, most of the folks I know who are making MMOs think there are only 7, just like my basic tools:

You could probably argue that some of those object types are really just embellishments of others as well, so maybe it's more like 5:

Kill something/prevent something from dying

Acquire Objects

Talk to NPCs/Deliver objects to NPCs

Interact with Objects in the World

Travel to locations/waypoints

In either case, that's a pretty restrictive collection of things a player can do, right? There are only so many combinations of those objectives you can string together before a player has essentially done every quest you can imagine, mechanically. In other words, if you've played an MMO with questing, there's a good chance you've already played every type of quest you could possibly think of. Even on a small game, this is true: there were thousands of quests in Auto Assault across the three factions, but all of them used objective types listed above and pretty much nothing else. So how does a designer use these simple quest types to make interesting content?